Van type rotary hydraulic transducer

ABSTRACT

A vane-type rotary hydraulic transducer, being a pump or a motor, in which a rotor equipped with vanes rotates within eccentric cam means which causes spaces between the vanes to expand and contract as the motor rotates, the spaces communicating with respective high and low pressure chambers when in different angular positions, and a pressure intermediate the pressures in these chambers being applied to the spaces between blades when they are positioned between said angular positions.

United States atem n91 Suzuki et al.

[ Oct. 2, 1973 [22] Filed:

[ VAN-TYPE ROTARY HYDRAULIC TRANSDUCER [75] Inventors: Noboru Suzuki; Uichi Yuki, both of Ibaragi-ken, Japan [73 Assignee: Yuken Kogyo Company Ltd.

May 10, 1971 211 Appl. No.: 141,728

[30] Foreign Application Priority Data July 9, 1970 Japan 45/59509 [52] US. Cl 418/80, 418/82, 418/180 [51] Int. Cl...... F0lc 21/00, F030 3/00, F04c 15/00 [58] Field of Search 418/80, 82, 180,

[56] References Cited UNITED STATES PATENTS Adams et a1 418/80 Kendrick 4121/82 8011 et a1 418/82 Primary Examiner-Carlt0n R. Croyle Assistant ExaminerJ0hn .l. Vrablik AttorneySteinberg & Blake [57] ABSTRACT A vane-type rotary hydraulic transducer, being a pump or a motor, in which a rotor equipped with vanes rotates within eccentric cam means which causes spaces between the vanes to expand and contract as the motor rotates, the spaces communicating with respective high and low pressure chambers when in different angular positions, and a pressure intermediate the pressures in these chambers being applied to the spaces between blades when they are positioned between said angular positions.

4 Claims, 5 Drawing Figures VAN-TYPE ROTARY HYDRAULIC TRANSDUCER FIELD OF THE INVENTION This invention relates to single-stage vane-type rotary hydraulic transducers, i.e., pumps and motors.

BACKGROUND OF THE INVENTION In conventional single-stage vane pumps, the maximum fluidpressure cannot usually be raised above 210 kg/cm This may be attributed to the decrease in expansion and contraction efficiency with increased'pressure due to fluid leakage, the variable contact pressure between the slidably mounted vanes and the cam ring circumference on the low pressure side, and the decreased mechanical rigidity of such vanes when slidably mounted in slots in the rotor.

SUMMARY OF THE INVENTION An object of the present invention is to reduce the drawbacks of conventional vane-type motors and pumps.

The invention provides a vane-type transducer which is so designed and arranged that the fluid gathered in a substantially annular fluid-chamber space defined by the rotor and the cam ring is exposed to an intermediate fluid pressure in the course of its volumetric expansion and contraction, the said intermediate fluid pressure being lower than the fluid pressure on the high pressure side of the transducer and higher than the fluid pressure on the low pressure side, when the transducer is located conventionally in a hydraulic circuit.

A preferred embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings showing a preferred embodiment thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a vane pump according to the invention, taken along line II of FIG. 4 in the direction of the arrows;

FIGS. 2 and 3 are front elevations of segments which make contact with respective end faces of the rotor in the pump shown in FIG. 1; and

FIGS. 4 and 5 are partial end views of the rotor showing the vanes thereof in two operating positions, the views being taken along line IVIV of FIG. 1.

DESCRIPTION OF SPECIFIC EMBODIMENT The vane pump shown in the Figures comprises a casing 1 having a fluid inlet opening 2 and a fluid outlet opening 3. A driving shaft 4 connected to a pumpdriving motor (not shown) is rigidly connected to a rotor 5 carrying a number of blade-like vanes 7 (see FIGS. 4 and 5) round its periphery. These vanes 7 are slidably received in radial slots in the rotor 5 and, when the rotor5 is set into rotation with the drive shaft 4, are urged outwards under centrifugal action into physical contact with the cam ring 6 positioned about the rotor 5, in a well-known manner.

At both ends of the rotor, there are arranged blocks or segments 8, 9 shown in FIGS. 2 and 3 respectively, which are provided with duct means communicating with outlet opening 3 and with a fluid pressure reducing means 10, which latter is adapted to deliver part of the exhaust fluid at a reduced pressure to the base portions of the vanes 7, as will more fully be disclosed hereinafter.

The exhaust fluid from the pressure reducing means 10 is delivered via duct 13 bored through the housing 1 to an annular groove formed at the exterior of seg ment 8 and communicating with two inlet ports 11 leading into a pair of sector-shaped recesses 12 formed on the end surface of the segment 8. Said inlet ports 11 are connected, as shown in FIG. 2, hydraulically with four inlet ports 14 through ducts 15, said ports 14 opening at equally spaced points onto the end surface of the segment 8.

As can be seen from FIGS. 4 and 5, an annular oilchamber space is defined by the rotor S and the cam ring 6, having a greater cross-section where it communicates with the low pressure chamber connected hydraulically with the inlet opening 2 and a lesser crosssection where it communicates with the high pressure chamber 18 connected hydraulically with the outlet opening 3. The above-mentioned inlet ports 14 open into the zones of the said oil-chamber space having a medium cross-section, i.e., between the larger low pressure zone andthe smaller high pressure zone.

Thus, referring to FIGS. 4 and 5, the fluid pressure prevailing in the enclosure or space a or b defined by two adjoining vanes 7 is kept lower than the fluid pressure at the outlet opening 3, on account of the direct fluid communication of the said enclosure a or b with the pressure reducing means 10. As more fully dis closed hereinafter, when the rotor 5 revolves, the fluid drawn from inlet opening 2 into the annular space, at

'a reduced suction pressure in the case of a vane pump located in a hydraulic circuit, and forced through the outlet opening 3 at an elevated discharge pressure is subjected to a pressure intermediate those two pressures by means of said pressure-reducing means 10, thus reducing the loads sustained by the vanes 7.

The intermediate fluid pressure prevailing in said en closure 0, b is selected to be lower than that prevailing at the outlet opening 3 and higher than that at the inlet opening 2. When the present invention is adapted to a fluid motor, the intermediate fluid pressure in said enclosure 0 or b is selected to be higher than the outlet fluid pressure and lower than the inlet fluid pressure.

As seen from FIG. 1, said duct 13 is kept from hydraulic communication from the intake opening 2 and the outlet opening 3, even when the vanes 7 are set into operation by rotation of the drive shaft 4.

In the drawings, numeral 17 denotes arcuate grooves on the end surface of the segment 8, which are kept by way of passages 17a (FIGS. 1 and 2) in fluid connection with the high pressure duct or chamber 18 for outlet fluid, numerals 19 and 20 denote pistons of the larger and lesser diameters, respectively, fitted in the pressure reducing device 10, numeral 21 denotes a sleeve or casing, numerals 22, 23 denote sleeve or casing covers, numeral 24 denotes a drain duct on the pump suction side communicating with the space 24a where the pistons 19 and 20 engage each other, nu-

operate, but the vanes 7 are pressed onto the cam ring circumference by centrifugal action.

Part of the outlet fluid at raised pressure is delivered into said arcuate grooves 17 on the rotor S from duct or chamber 18 through passages 17a, and also into said fluid pressure reducing means through passage 13a (FIG. 1). The fluid at elevated pressure which enters into the pressure reducing means 10 through the passage 13a reaches a chamber which houses a spring at the right end of piston 20, as viewed in FIG. 1. This spring acts on the piston 20 to displace the latter to the left, as viewed in FIG. 1, thus fully opening, when the parts are at rest, the bore 13 as well as a passage in the casing 21 which provides communication between the right end of the piston 20 and thee end chamber 19a which communicates with the left end of the larger piston 19.

During an initial stage of the operation, the high pressure fluid acts on the end of piston 19 in chamber 19a. This end of piston 19 has a larger area than the right end of piston 20 which is also exposed to the high pressure fluid. Because the spring engaging piston 20 is relatively weak and because chamber 24a receives only low pressure fluid, pistons 19 and 20 advance to the right (FIG. 1). As a result of this action the pistons 19 and 20 assume an equilibrium position where fluid at reduced pressure reaches the bore 13. The outlet fluid, thus reduced in pressure to an intermediate value by said pressure reducing means 10, is supplied into said sector-shaped recess 12 so as to act on the inner portions of the vanes 7 located in the low pressure fluid suction zone of the annular oil-chamber space. Thus, it will be seen from FIG. 4 that the space 12 of segment 8 is angularly aligned with the suction inlet 2 while the high pressure discharge ducts 18 are angularly spaced between the recesses 12, as is particularly apparent also from FIG. 2. However, the recesses 17 which receive the high pressure fluid deliver the high pressure fluid to the inner ends of the vanes 7 when they are located at the high pressure zones, so that as the vanes 7 rotate they are urged outwardly by an intermediate pressure at the low pressure zones of the pump and at a high pressure at the high pressure zones of the pump. Furthermore, since the intermediate pressure recess 12 is separated from the high pressure recesses 17 only by the narrow surface areas 17b at the end surface of the segment, 8, some of the-high pressure fluid delivered through the openings 17 to the inner ends of the vanes leaks in the form of a film radially inwardly across the surface areas 17b into the intermediate pressure space 12 so that the latter is additionally supplied with fluid at an intermediate pressure byway of leakage from the openings 17. Intermediate pressure outlet fluid is also supplied into said enclosures a, b through said inlet ports 14 hydraulically connected with said'ports 11 through ducts 15.

Assuming that the exhaust fluid pressure and the intermediate fluid pressure from the pressure reducing means 10 are equal to p and p Ap, respectively, the fluid pressures at enclosures c, a and d (FIG. 4) are equal to the fluid suction pressure, p Ap, and p, respectively, while the fluid pressures at enclosures e, b and fare equal to p, p Ap and the fluid suction pressure (see FIGS. 4 and 5).

As will be apparent from the foregoing, those fluid enclosures between vanes which are at elevated fluid pressures are adjacent fluid enclosures exposed to the intermediate fluid pressure, so that fluid leakage is reduced. Moreover, any fluid shifted from an enclosure at the elevated fluid pressure into an enclosure at the intermediate fluid pressure by leakage can be recovered into the former enclosure by the pumping action on the bottom portions of the vanes, so that the vane pump volumetric efficiency tends not to decrease to a marked degree even when the pump is operating under high fluid pressure conditions.

The table below shows the results of experiments conducted on the volumetric efficiency of a vane pump manufactured for trial by the applicant.

Oil used: DHF 44 Fluid As the fluid pressure acting on the inner portions of the vanes in the fluid suction or low pressure zone is the intermediate fluid pressure above referred to, the urging pressure exerted by such vanes on the cam ring can effectively be decreased. FIG. 4 illustrates how the inner ends of the rotor slots which receive the vanes 7 communicate not only with the intermediate pressure space 12 but also with the high-pressure outlets 17. Moreover, referring to FIG. 4, the fluid load applied to the vane 7a just exposed to the outlet fluid pressure is equally divided between it and the preceding vanes 7b, 7c, thus enabling the described vane pump to bear higher fluid pressures than in the case of the conventional single-stage pump. In addition, until such time as the vane is exposed to the enhanced pressure from the outlet opening 3, the vanes 7a, 7b that follow are maintained at the medium fluid pressure, thus obviating abrupt fluid pressure changes and minimizing the accompanying mechanical sounds and pulsating vane movements.

As has been indicated above, the structure of the invention can operate either as a pump or motor. This structure includes the housing means 1, 26 formed with the high-pressure part 3 to which high pressure fluid is delivered when the structure operates as a pump and which receives high pressure fluid when the structure operates as a motor. Also, the structure is formed with the low-pressure port 2 into which fluid is sucked when the structure operates as a pump and to which fluid is delivered when the structure operates as a motor. The housing means 1, 26 carries in its interior the pair of slide portions 8, 9 which have inner surfaces, respectively visible in FIGS. 2 and 3, directed toward each other and slidably engaging the opposed faces of the rotor 5 which is formed with the vane slots which extend inwardly beyond the vanes 7, the latter projecting outwardly beyond the slots into engagement with the inner surface of the cam means 6 which is situated within the housing means 1, 26 and which surrounds the rotor. The housing means 1, 26 including the interior slide portions 8, 9 are formed with low-pressure passages providing communication between the lowpressure port 2 and spaces between the vanes and between the rotor 5 and the cam means 6 during one part of the angular rotation of the vanes, the housing means 1, 26, including the slide portions 8, 9, also being formed with high-pressure passages communicating with the space between the rotor 5 and the cam means 6 and with the spaces between the vanes during another part of the angular movement thereof during each rotation. The slide portions 8, 9 are provided at their inner surfaces which slidably engage the opposed faces of the rotor 5 with high-pressure recesses 17 which communicate directly with the high-pressure passages, such as the passagees 18, for supplying high-pressure fluid directly from the high-pressure passages to the inner ends of the vanes in the vane slots of the rotor 5 during the time that the vanes have the spaces therebetween in communication with the high-pressure passages. These slide portions 8, 9 are foremd with intermediatepressure recesses 12 which also communicate with the high-pressure passages 18, but only through the pressure-reducing means 10, and these intermediate pressure recesses 12 communicate with the inner ends of the vane slots for delivering intermediate-pressure fluid thereto for urging the vanes outwardly toward the cam means at an intermediate pressure, the inner ends of the vane slots communicating with the intennediate pressure recesses only during the time that the spaces between the vanes communicate through the lowpressure passages with the low-pressure port 2. During the time that the successive vanes travel from a region where they communicate with the low-pressure to a region where they communicate with the high-pressure port they communicate through the passages 14 in the slide portions 8, 9 also with the intermediate pressure recesses 12, so that in this way fluid at intermediate pressure is supplied to the spaces between the vanes as they travel between regions respectively communicating with the low and high pressure ports. In addition, the intermediate pressure recesses 12 have portions situated inwardly of the high-pressure recesses 17 so that leakage fluid flows from the high-pressure recesses 17 across the surface-portions 17b of the slide portions 8, 9 into the intermediate pressure recesses 12 so that the latter are supplied with fluid at intermediate pressure also by way of leakage from the high-pressure recesses at the interface between the slide portions 8, 9 and the opposed side faces of the rotor 5.

We claim:

1. In a structure capable of operating either as a pump or motor, housing means formed with a lowpressure port and a high-pressure port, a rotor supported for rotary movement in said housing means and having opposed side faces and being formed at its periphery with radial vane slots, a plurality of vanes situated in said slots for slidable movement radially therein, said slots extending inwardly beyond said vanes and said vanes extending outwardly beyond the periphery of said rotor, cam means situated in said housing means and surrounding said rotor, said cam means having an inner camming surface engaged by the outer tips of said vanes while they rotate with said rotor for displacing fluid between high and low pressure zones situated between said cam means and rotor, a pair of slide portions situated in said housing means and having directed toward each other slide surfaces which slidably engage said opposed side faces of said rotor,

said housing means being formed with a low-pressure passage communicating with a low-pressure zone between said rotor and cam means and with said lowpressure port and said housing means and slide portions being formed with a high-pressure passage communi cating with a high-pressure zone between said rotor and cam means and with said high-pressure port, said slide portions being formed with high-pressure recesses angularly aligned with said high-pressure zone and communicating directly with said high-pressure passage and with inner ends of said vane slots to deliver to the latter from the high-pressure passage fluid at high pressure to urge the vanes outwardly during the time that they travel through a high-pressure zone, and said slide portions being formed at their inner surfaces in angular alignment with said low-pressure zone with intermediate pressure recesses communicating with the inner ends of said vane slots, and pressure-reducing means carried by said housing means and communicating with said high-pressure passage for receiving high-pressure fluid therefrom, said housing means and slide portions being formed with intermediate pressure passages communicating with said pressure-reducing means and said intermediate pressure recesses, said pressure-reducing means delivering fluid at intermediate pressure to said intermediate pressure passages from said high-pressure passage so that during the time that the vanes travel through a low-pressure zone they are urged outwardly toward said cam means at an intermediate pressure by intermediate-pressure fluid received at the inner ends of the slots from said intermediate pressure recesses of said slide portions, said intermediate pressure recess of each slide portion having a portion situated radially inwardly of said high-pressure recess of each slide portion and separated therefrom by a relatively narrow surface area situated radially between said highpressure recess and said portion of said intermediate pressure recess of each slide portion and forming between said rotor and each slide portion an interface across which fluid leaks radially inwardly toward the rotor axis from said high-pressure recess of each slide portion to said portion of said intermediate pressure recess thereof to deliver to each intermediate pressure recess fluid at intermediate pressure in addition to the fluid received from an intermediate pressure passage.

2. The combination of claim 1 and wherein said rotor and cam means define between themselves an intermediate zone through which the vanes travel when rotating between the high and low pressure zones, and said intermediate pressure passages communicating also with said intermediate zone for delivering fluid at intermediate pressure to the spaces between the vanes as they travel through the intermediate zone between the rotor and cam means.

3. The combination of claim 1 and wherein said intermediate pressure recess of each slide portion extends completely around the axis of said rotor and has said portion situated radially inwardly of said high-pressure recess angularly displaced with respect to another portion of said intermediate pressure recess which is in angular alignment with said low-pressure zone.

4. The combination of claim 3 and wherein said other portion of each intermediate pressure recess which is in angular alignment with said low-pressure zone being situated at the same radial distance from said rotor axis as said high-pressure recess of each slide portion.

I! It t i 

1. In a structure capable of operating either as a pump or motor, housing means formed with a low-pressure port and a highpressure port, a rotor supported for rotary movement in said housing means and having opposed side faces and being formed at its periphery with radial vane slots, a plurality of vanes situated in said slots for slidable movement radially therein, said slots extending inwardly beyond said vanes and said vanes extending outwardly beyond the periphery of said rotor, cam means situated in said housing means and surrounding said rotor, said cam means having an inner camming surface engaged by the outer tips of said vanes while they rotate with said rotor for displacing fluid between high and low pressure zones situated between said cam means and rotor, a pair of slide portions situated in said housing means and having directed toward each other slide surfaces which slidably engage said opposed side faces of said rotor, said housing means being formed with a lowpressure passage communicating with a low-pressure zone between said rotor and cam means and with said low-pressure port and said housing means and slide portions being formed with a highpressure passage communicating with a high-pressure zone between said rotor and cam means and with said high-pressure port, said slide portions being formed with high-pressure recesses angularly aligned with said high-pressure zone and communicating directly with said high-pressure passage and with inner ends of said vane slots to deliver to the latter from the high-pressure passage fluid at high pressure to urge the vanes outwardly during the time that they travel through a high-pressure zone, and said slide portions being formed at their inner surfaces in angular alignment with said low-pressure zone with intermediate pressure recesses communicating with the inner ends of said vane slots, and pressure-reducing means carried by said housing means and communicating with said high-pressure passage for receiving highpressure fluid therefrom, said housing means and slide portions being formed with intermediate pressure passages communicating with said pressure-reducing means and said intermediate pressure recesses, said pressure-reducing means delivering fluid at intermediate pressure to said intermediate pressure passages from said high-pressure passage so that during the time that the vanes travel through a low-pressure zone they are urged outwardly toward said cam means at an intermediate pressure by intermediate-pressure fluid received at the inner ends of the slots from said intermediate pressure Recesses of said slide portions, said intermediate pressure recess of each slide portion having a portion situated radially inwardly of said high-pressure recess of each slide portion and separated therefrom by a relatively narrow surface area situated radially between said high-pressure recess and said portion of said intermediate pressure recess of each slide portion and forming between said rotor and each slide portion an interface across which fluid leaks radially inwardly toward the rotor axis from said highpressure recess of each slide portion to said portion of said intermediate pressure recess thereof to deliver to each intermediate pressure recess fluid at intermediate pressure in addition to the fluid received from an intermediate pressure passage.
 2. The combination of claim 1 and wherein said rotor and cam means define between themselves an intermediate zone through which the vanes travel when rotating between the high and low pressure zones, and said intermediate pressure passages communicating also with said intermediate zone for delivering fluid at intermediate pressure to the spaces between the vanes as they travel through the intermediate zone between the rotor and cam means.
 3. The combination of claim 1 and wherein said intermediate pressure recess of each slide portion extends completely around the axis of said rotor and has said portion situated radially inwardly of said high-pressure recess angularly displaced with respect to another portion of said intermediate pressure recess which is in angular alignment with said low-pressure zone.
 4. The combination of claim 3 and wherein said other portion of each intermediate pressure recess which is in angular alignment with said low-pressure zone being situated at the same radial distance from said rotor axis as said high-pressure recess of each slide portion. 